Some time later, back at the cemetery, Regis is starting to recover from his transformation. You can optionally ask about what happened, before mentioning that you finished the brew. You’re given the resonance, and slip into a deep trance.
Waking up, you explain that you saw visions of the death of de la Croix; it did not come easy. After chopping up the body, Dettlaff was overcome with remorse, and slicing off the hand that had committed the murder. You can also mention the vision of where the Count and Dettlaff first met. Then mention your vision began and ended with a bootblack’s stand. Somewhere in the port district. A chat with the lad at the stand is your only lead. The quest now concludes.